1. Field of the Invention
This invention relates to a pendulum arrangement for a clock movement, and more particularly to a bearing device for a pendulum arm.
2. Description of the Prior Art
The pendulum arrangement for the clock movement has conventionally formed one of the important portions of pendulum clocks as a time standardizing oscillator and has been widely used for decoration even in the modern electronic clock in which a crystal oscillator or the like is installed.
This known pendulum arrangement has a pendulum arm supporting means 10, as shown in FIG. 1, which is provided on a clock movement housing so that a pendulum arm 12 swings freely. In FIG. 1 the pendulum supporting means has a V-shape groove 10a in which a knife edge 12a of the pendulum arm 12 is supported. A pendulum 14 is provided at the lower end of the pendulum arm 12, but the swinging movement of the pendulum arm 12 and the pendulum 14 continues by the electromagnet driving force produced between a magnet 16 and a coil 18 which is attached on the clock movement housing. The swinging state of the pendulum arm 12 is shown by chain lines in the Figure.
In FIG. 2 shown therein is a supporting state between the pendulum arm supporting means 10 and the pendulum arm 12 when the clock movement is set in the vertical line in the right way. As is evident from Figure, the pendulum arm 12 can swing an equal angular amount .theta. in both directions and this angular amount .theta. is determined to be larger than the ordinary swinging angular amount of the pendulum arm.
Accordingly, in an ordinary state the swinging movement of the pendulum arm 12 and the pendulum 14 can be obtained in good conditions. This known prior art pendulum arrangement, however, has the disadvantage that the pendulum movement cannot be performed properly or at all when the clock movement is set on an inclined surface.
In FIG. 3 shown therein is a state that the clock movement or the supporting means 10 is set at an inclination .theta..sub.0 relative to the perpendicular line. At this time, as evident from Figure, in a swing to one direction, that is, to a clockwise direction in Figure, the pendulum arm is limited in its swing angular amount to the amount (.theta.-.theta..sub.0). The pendulum arm 12, therefore, comes in touch with the V-shape groove 10a of the supporting means 10 so that it swings in an unstable state or cannot swing at all.